1. Field of the Invention
The present invention relates to a system for sealing air handling ducts, particularly those air ducts that are located in a cement slab floor or under a slab floor.
2. Description of the Related Art
Slab floor buildings normally have the heating and air conditioning air ducts located in the cement slab floor of the building. If the building experiences structural problems, such as a cracked foundation, or has moisture and rust in the ducts, the most common remedy for these problems is to abandon the existing duct system and install a new duct system and new equipment in the ceiling of the building. Then the old abandoned duct system is normally closed off by pouring cement into the duct openings.
The problems associated with this solution are that installation of a new duct system is time consuming, expensive, and can be extremely difficult, particularly if the building is more than one story high.
Instead of replacing the duct system, a more cost effective and less disruptive solution would be to provide some type of liner for the existing duct system that would have structural integrity, i.e. be air and water tight, and would fill in any gaps or holes in the existing duct system caused by movement in the surrounding cement slab. Also, such a sleeve should be easy to install at normal atmospheric temperatures, be inert so that it provides a clean, flame-resistant, sanitary, and stable surface for carrying air throughout the building.
The present invention answers this need in that it is a relatively fast, easy, and inexpensive method of repairing an existing air duct by providing a lining on the interior surfaces of the existing air duct system. The liner is installed according to the present invention at normal atmospheric temperatures and quickly cures to a tough, smooth, and inert surface that is air and water tight. The present liner is effective in filling in gaps or holes that may be present in the duct system due to movement in the surrounding concrete slab and completely covering and sealing rust, mold, or mildew resulting from the presence of moisture in the ducts.